The last article described viruses and explained their impact on the human organism. This blog post deals with our immune system and how it keeps our body healthy. Some of these mechanisms are given to us at birth; our organism has to learn another part of the body's own defense system. With the right lifestyle we can strengthen our immune system.

What is meant by the immune system?

The body's own defense system prevents or makes it more difficult for pathogens to enter. Intruders, foreign cells, foreign substances, defective body cells (e.g. cancer cells) and virus-infected cells are eliminated. The immune system is very complex and consists of various components and mechanisms 1 .

Non-specific immune defense – the innate resistance to pathogens

 Non-specific defense refers to all innate mechanisms that protect the body. As the word “unspecific” suggests, it is a system that filters rather superficially and is not specialized for specific pathogens.

Chemical and mechanical barriers ensure that many potential pathogens cannot even get inside us. On the one hand, our skin surface is a mechanical limit, but on the other hand it is also a chemical one, as it has a natural protective acid mantle microorganisms is covered, which repel foreign substances and organisms. It is similar with our mucous membranes.
With its low PH value, stomach acid ensures that potential pathogens that enter the digestive tract through food are destroyed. The tears in our eyes contain lysozymes that can dissolve bacterial walls. The cilia in our airways catch larger particles from the environment (such as fine dust) and transport them back out. Coughing and sneezing supported this. Diarrhea and vomiting are also defense mechanisms that transport unwanted things out again 1 .

On cellular level It looks like we have white blood cells from the start, which are part of our immune system. They are divided into different types, important for the immune system are the B cells, which include the following subgroups: The phagocytes eliminate residual bacteria and dead cells, like a cookie monster eating annoying crumbs. The T killer cells destroy infected cells so that they cannot infect others 2 .

From the biological perspective one also speaks of the humoral level , this refers to ours Body fluids . Proteins contained in them bind to potential pathogens and are activated. The mechanisms already mentioned such as gastric juice, tear fluid and their enzymes or mucus from the airways are part of this. Inflammatory reactions are typically used to ward off foreign substances. When there is inflammation, the capillaries expand so that the tissue becomes more permeable. In this way, the enzymes and proteins can mark the potential pathogens and the phagocytes are attracted, which then eliminate the foreign substances.

Specific immune defense – The acquired immunity to pathogens

In contrast to the non-specific immune system, the specific immune system must first acquire its capabilities. If the innate defense mechanisms have failed, the specific immune defense kicks in. Because not all pathogens can be detected or kept away so quickly. The following also applies here: the smaller the pathogenic invaders, the greater the challenge for the immune system. Viruses in particular usually find a way to cross our barriers and enter the organism 1 .

The pathogens must then be recognized in the lymphatic system using the trial and error system. The way it works is that there are many of the white blood cells mentioned above floating around in the lymph organs and lymphatic streams at all times. These T cells and B cells have special receptors on their surface Antibodies . These all have different structures, each of them waiting for one antigen of a pathogen comes and binds to them. This works according to the key-lock principle. The receptors on the lymphocytes represent the lock here and a key in the shape of the pathogen floats around until it finds its lock and unlocks it, or is thus bound to the respective defense cell.

Here, too, there is a cellular and a humoral level: viruses in particular attack body cells. The infected cells are then recognized on their surface by the immune system and destroyed by T killer cells. In terms of humor, viruses, but also toxins and bacteria are again important. The same key-lock principle is used in the blood and lymph, except that these cells are slightly different. But these also have their antibodies on their surface. In the end, intruders can be killed and eliminated by the phagocytes as with non-specific defense 2 .

Immunity arises after an initial infection has been successfully fought

Once the immune system recognizes which cell has the appropriate antibody to bind to the pathogen, it begins to multiply that cell. With the help of the resulting army of defense cells, the respective viruses or bacteria can be destroyed on a large scale. Smaller helper cells are also involved in this process, which then develop into so-called memory cells. After the fight, these are our data storage, where an already known pathogen can be eliminated much more quickly in the event of a new infection. It is obvious that the process of an initial infection takes longer and longer and can therefore often lead to symptoms of illness. The specific defense is referred to as: Immunity when the body has set up this storage system and will no longer become ill again if the same pathogen appears again 2 .

However, the whole thing is relatively complex and flu viruses in particular often constantly change a little, so that our body no longer recognizes the mutated virus and the process just described has to go through again.

Fever – an intelligent and important mechanism of our immune system

When our immune system is activated, our body expends energy to raise our temperature. When we are sick or experience symptoms, we often have a fever. This is often the case, especially with illnesses caused by viruses. The increased temperature has a defense benefit: although it usually does not kill germs, it does accelerate the elimination of toxins that remain in the immune processes. Fever-reducing medications are counterproductive because they can hinder the work of the immune system. Of course, you always have to weigh this up individually, because high fever temperatures such as 42⁰ C can be life-threatening, but below 40⁰ C there is usually no danger 2 .

Our immune system is strengthened through physical regeneration?

The most important thing that keeps us healthy is the balance between our activity Sympathetic nervous system and Parasympathetic nervous system . If the body is in the sympathetic nervous system, it is ready to perform, focused and rather under tension. To do this, the corresponding hormones or neurotransmitters are released, which give the body signals that it needs to prepare for active and rather strenuous tasks. In this state, for example, digestion and repair processes in the cells are reduced. These procedures are active again as soon as the body is in relaxation and regeneration mode, namely in the parasympathetic nervous system. The organs that release stress and activation hormones can recover and the organism focuses on the things that promote our health and replenish our storage 3 .

So it is obvious how important it is that we are regularly in this regeneration mode:
The actions of our immune system described above are primarily active in the parasympathetic state. But if our body is constantly under stress, be it mental or physical, many phases in which these processes can take place are missing.

How can the parasympathetic nervous system be used to promote the immune system?

  • Short and intense Sports units cause our body to switch to the parasympathetic nervous system immediately after training. After physical exertion, he receives the right signals that he now needs to recover. More on this here !
  • Gut health is an important factor that supports our immune system. On the one hand, because the intestinal mucosa, as described at the beginning, is a chemical and mechanical barrier that protects us directly from pathogens. On the other hand, because a chronically inflamed intestinal mucosa means stress and constant inflammatory reactions. We digest primarily in the parasympathetic nervous system and the renewal and regeneration of the cells also occurs in this state. You can find out more about intestinal health here !
  • The right ones nutrient give our cells important signals; Nutrition has a much greater importance for our body than just providing energy. The most common potential allergens such as cow's milk, grains containing gluten and soy as well as sugar can trigger chronic inflammation in us. These cause our immune system to constantly focus on this instead of being able to protect us from real pathogens. This weakens the immune system.
    Protein, essential fatty acids and micronutrients such as zinc, vitamin D3, vitamin C and antioxidants maintain our cells sustainably and protect them at the same time. If these are all present in the body, the immune cells are also strengthened. So it makes sense to adopt a diet that includes lots of vegetables, high-quality protein sources and healthy fats. More about Breakfast theme & for the Topic fats !
  • Our Mindset has a decisive influence on dealing with external stressors. Anyone who learns to deal with them correctly and think positively supports the regeneration of the organism. Simple and short daily routines such as keeping a gratitude diary or yoga and meditation sessions promote a positive mindset and thus also the regular switching to the parasympathetic nervous system. More on this here !


Our immune system consists of an innate and learned system. It can fight pathogens and sometimes has to activate inflammatory processes in the body and increase body temperature in order to eliminate the invaders as efficiently as possible. We can actively support these processes through a healthy lifestyle by getting enough exercise, consuming the right foods and integrating conscious relaxation phases into our everyday lives.

1 Bütikofer, Markus; Hopf, Zensi; Rutz, Guido; Stach, Silke and Grigoleit, Andrea (2015): Human Biology 1: Basics, Metabolism and Defense Systems. Zurich: Compendio Educational Media. pp. 134-188.

2 Zschokke, Samuel (2018): Human Biology I: Anatomy and Physiology – Immune System to Defend Disease. Basel: University of Basel.

3 Fiedler, Annett (2019): The parasympathetic patron saint for health.
[; April 14, 2020]

Ines Schulz
Ines Maria Schulz, born on December 1st, 1992 in Basel, Switzerland, also completed her Master of Education in Biology and WAH there, laying the foundation for the understanding of physiology and anatomy as well as nutrition. She is also a trained primary school sports teacher. For two years she has been a coach at MTM Personal Training, the most successful personal training studio in Berlin. There she supports customers every day who want to exploit their maximum potential in terms of mental and physical health and performance. In cooperation with doctors like Dr. Dominik Nischwitz and a laboratory for intestinal health as well as the constant exchange within the team, she can provide her customers with optimal advice about training, nutrition, micronutrients and lifestyle. She has already written a breakfast book and a large part of a lifestyle booklet for MTM. She also writes the weekly newsletter, which publishes nutritional tips and recipes she has created. Ines has completed seminars and certificates with a variety of successful coaches and specialists and is constantly expanding her skills. The young trainer has been writing blog articles for Supz Nutrition since January 2019.

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